The present invention relates to frames of the type having a generally open-sided construction making possible the loading of two or more tiers of vehicles onto the frame and which, after being loaded, are adapted for insertion into a standard cargo-carrying container for shipment. In particular the present invention relates to improvements in this basic type of frame that enable better utilization of lengthwise container space.
Frames of the above-referenced basic type are shown, for example, in Gearin, et al. U.S. Pat. Nos. 4,768,916 and 4,797,049. In each of these references, the frame shown is of a generally open-sided box-like construction where each side of the frame includes a longitudinally-extending upper and lower rail. At the corners of the frame and at longitudinally-spaced positions therebetween, upright brace members are used to connect together the upper and lower rails. At the ends of the frame, the sides are connected together such as by a spreader bar or by a two-panel centrally-hinged gate that is capable of being folded inwardly in order to collapse the sides of the frame.
In order to support vehicles on the above-described type of frame, respective pairs of elongate wheel cradles are suspended across the respective sides of the frame to support the forward and rearward wheels of each vehicle. In particular, each end of each wheel cradle is supported by an end hanger which, in turn, is vertically slidable and adjustably lockable along a post member suspended by its upper end from the upper rail of the frame. The vertical slidability of the end hangers makes possible power-assisted vertical lifting of each vehicle by the hangers. The upper ends of the respective post members are, in turn, longitudinally movable along the upper rails in order to compensate for differences in vehicle wheel base as well as to allow tilting of the vehicles. An elongate plate having numerous openings or slots spaced therealong is affixed to the inward edge of each upper rail, each opening or slot providing a different pinning or locking position for each post member.
A difficulty with the basic type of frame just described arises because of the differing sizes of containers that are encountered at different vehicle loading and unloading stations. In particular, cargo-carrying containers that are 40 feet, 45 feet, or 48 feet in length may be encountered. The frames of the basic type described, being of fixed dimension, are required to have a length no longer than that which will fit within the shortest container. Accordingly, there is the possibility of collision or shock damage to the containers, the frame or to the vehicles loaded on the frame during to-and-fro movement of these frames within longer-length containers during transport. Moreover, even if a movement-limiting mechanism is provided to limit such to-and-fro movement, there is still the problem of the reduction in the number of vehicles that can be shipped in the longer-length containers over what might otherwise have been shipped in such containers. For example, whereas normally only three larger-sized vehicles can be carried on each frame when each frame is 39 feet in length (suitable for a 40-foot container) if, instead, the frames were to be 47 feet in length (suitable for a 48-foot container) it might be possible to carry as many as six larger-sized vehicles.
In view of the foregoing, there is a need for a vehicle-carrying frame having an improved design that enables fuller use of the available space inside each different size of transport container. Conceivably, for example, auxiliary sections which attach to the ends of the basic frame could be used for selectively extending that frame's length. However, such sections would be unwieldy to handle and could pose a falling hazard to operator and equipment alike since each section would presumably need to be as tall as the frame, of three to five feet in length, and of sufficient structural bulk to support vehicles along its sides. In any improved design, there should be a minimal risk of operator injury, whether such risk is a result of falling hazards or of other type of hazards. It is preferable, for example, to avoid having any mechanism which has pairs of members that close by angular movement to a position alongside .each other, for such a mechanism, when used by an inattentive operator, may pose a pinching-type hazard.
In addition to the above safety-related concerns, there are also efficiency concerns relating to the time needed for setup. For example, when setting up the frame for use in a container of a length different than that in previous use, preferably it will not be necessary to disassemble and reassemble major portions of the frame.
In order to flexibly ensure maximum utilization of lengthwise container space, it is desirable that any improvement to the basic frame retain the capacity of that frame for accommodation of varying-length vehicles. It is desirable, in other words, that the lengthwise space of any improved frame be capable of flexible allocation so that a vehicle of very large length, such as a limousine, can be supported endwise of a vehicle of very small length, such as a subcompact. In this manner, full use can be made of the available lengthwise space without any practical limits being imposed on the lengths of the vehicles being carried. Such capability is not available, for example, on vehicle-carrying frames of the type shown in Swartzwelder, U.K. Patent No. 1,006,496. In Swartzwelder, tiltable vehicle supports are used to conserve lengthwise frame space but the individual length of each support is fixed and must generally correspond, for economic reasons, to the average vehicle length in order that the Swartzwelder frame may efficiently carry the maximum number of standard-length vehicles. Frames of this type thus cannot be used for transporting vehicles of very large length, such as limousines, which have a length exceeding the average vehicle length.
Preferably, the extent of movement of a frame of improved design within its transport container will be less than that which is possible with the basic frame. Then, during transport of the improved frame, there will be less time for the container to acquire a velocity significantly higher or lower than that of the enclosed frame prior to any collision that might occur between the frame and the end walls of the container. As a result, the peak level of the shock forces generated during such collision will desirably be reduced.
During collision between a frame and its container, the structure most in need of protection is the end door of the container, which is typically made of lighter construction than the sides and opposite end wall of the container in order to facilitate handling of the door by the transport operator. The need for protection of the end door is particularly great during the return transport of empty frames. In practice, up to six side-by-side collapsed frames can be loaded at one time inside the container for return transport. The total mass of this large number of frames is even greater than that of a single frame which has been fully loaded with vehicles so that during the transport of empty frames, there is the potential for even larger shock forces to be generated.
One approach which has been used for limiting movement of the frame inside its container in order to protect against shock damage uses an L-shaped mechanism having adjustable vertical and horizontal portions. This mechanism, which was developed by one of the present applicants, mounts on each rear corner of the frame opposite the end of the container that includes the door. The possibility of shock damage to the door is completely foreclosed by the vertical portion, which adjusts in height so that the horizontal portion is raised above the door to a position extending across from the upper container margin that borders the door. Normally this upper margin is of heavier construction than the door itself and is therefore less susceptible to shock damage. Further protection against shock damage is provided by screw adjustment of the horizontal portion which brings the head end of that portion in close-proximity to the upper margin, thereby limiting the extent of movement of the frame within the container and reducing the peak levels of shock force generated during frame and container collisions.
However, the L-shaped structure of the mechanism just described can cause a large bending moment to develop across the upper lengthwise rails of the frame, causing this lengthwise assembly to buckle or crack, particularly since there is no attaching structure, such as the wheels found on the lower rails, through which this bending moment can be resolved. Furthermore, if an attempt is made to decrease the risk of structural damage to the frame by using heavier upper rails, this modification results in a more massive frame and the development of even greater shock forces, which forces will act in a cumulative manner on the container during the return transport of empty frames. Moreover, this L-shaped mechanism increases-the time needed in preparation for transport, particularly when there are several empty frames to be loaded inside the container, since each mechanism on each corner of each frame must be vertically and horizontally adjusted into its operative position proximate the upper margin to ensure that no shock damage occurs.
Another approach which has been used to provide protection to the container doors is the placement of removable cushioning pads between the container door and the frame. However, such pads are time-consuming to install. Also, to the extent that such pads are springably "stiff" enough to withstand the peak levels of shock force which can be generated, their placement makes it difficult to close the container door as necessary to wedge them into place. On the other hand, unless they are snugly wedged into place, such pads are able to work loose from their frame-blocking positions so that no protection at all is provided to the door.
Conceivably, both the problem of cushion slippage and the problem of difficult door closure could be solved by mounting hydraulic shock absorbers along the surface of the door where protection against shock damage is most needed. Surface-mounted shock absorbers of a type usable for this purpose, are available, for example, from Ace Controls, Inc. based in Farmington, Mich. As explained in their product catalog No. 48-10-91 (published in 1988), p. 8, contained inside such absorbers is a fluid that is forced through a series of narrow holes in order to absorb the force of impact. Accordingly, such absorbers would provide little opposition to a closing door provided that the door was closed gradually enough to allow sufficient time for the fluid to flow slowly through the narrow holes.
However, the type of shock-absorber just described is primarily intended for use in those applications where the exact point of impact is determined in advance, because one of the colliding bodies is on a track, or is otherwise limited to a predetermined path, as it travels toward the other body (refer, for example, to pages 34-41 of catalog No. 48-10-91 identified above). In the context of the present invention, sometimes less than the maximum number of empty frames are loaded into a container for return transport. Because these empty frames are not tightly packed together, their position can vary somewhat relative to the sides of the container, so that no stationary arrangement of shock-absorbers along the container door would adequately serve to protect the door. Moreover, shock-absorbers of the type described are relatively expensive, because of their close-tolerance, fluid-containing internal structures, and therefore do not appear practical for wide use.
Two further systems for preventing damage to container doors due to the movement of a cargo-carrying frame inside its container are shown in Hackney U.S. Pat. No. 3,667,635 and Kern U.S. Pat. No. 3,938,678. Hackney shows the use of a locking bar which has springably retractable ends. These ends fit into a pair of holes provided on opposite sides of the container adjacent the container door. The locking bar, therefore, blocks the approach of the frame toward the door. Kern shows a pin which drops through a hole provided on the lower rail of the frame into a hole provided within the floor of the container. The respective holes in the frame and the floor are so arranged as to keep the frame away from the door when the drop pin is in place. However, the door-protecting mechanisms of Hackney and Kern require that the cargo container be specially modified to receive the locking bar and drop pin, respectively. This approach is unworkable where the frame is to be shipped using preexisting modes of transport (e.g., by rail car, ship and truck) in which cargo containers of only a standard type are generally available.
Accordingly, an object of the present invention in at least preferred embodiments thereof is to provide a vehicle-carrying frame having an improved mechanism enabling fuller use of the available space inside each type of container which is to be used for transporting the frame.
A related object of the present invention in at least preferred embodiments thereof is to provide a mechanism of the above type that is compatible with flexible allocation of the lengthwise space of the frame in order to accommodate a wide range of vehicle sizes.
Another related object of the present invention in at least preferred embodiments thereof is to provide an improved mechanism for protecting the door of the above container against shock damage due to movement of the frame inside the container.